We investigate the problem of sequencing jobs that have multiple components. Each component of the job needs to be processed independently on a specified machine. We derive approximate algorithms for the problem of scheduling such vector jobs to minimize their total completion time in the deterministic as well as stochastic setting. In particular, we propose a Linear Programming and a Greedy he...

Understanding and managing water quality in drinking water distribution system is essential for public health and wellbeing, but is challenging due to the number and complexity of interacting physical, chemical and biological processes occurring within vast, deteriorating pipe networks. In this paper we explore the application of Self Organising Map techniques to derive such understanding from ...

Potential workers are classified as unemployed if they seek work but not working. The population contains two groups—those with jobs and those without jobs. Those on furlough or temporary layoff. This group expanded tremendously in April 2020, at the trough of pandemic recession. They wait out periods non-work understanding that their still exist will be recalled. We show resulting temporary-la...

Abstract In this paper, we consider the problem of scheduling a set of jobs on two parallel machines to minimize the sum of completion times. Each job requires a setup which must be done by a single server. It is known that this problem is strongly NP-hard. We propose two mixed integer linear programming models and a simulated annealing algorithm. The performance of these algorithms is evaluate...

We consider the problem of scheduling a set of jobs on a single machine with the objective of mimizing weighted (average) completion time. The problem is NP-hard when there are precedence constraints between jobs, [12] and we provide a simple and e cient combinatorial 2-approximation algorithm. In contrast to our work, earlier approximation algorithms [9] achieving the same ratio are based on s...

A deterministic server is shared by users with identical linear waiting costs, requesting jobs of arbitrary lengths. Shortest jobs are served ...rst for e¢ciency. When the server can monitor the length of a job, but not the identity of its user, merging, splitting or partially transferring jobs may o¤er strategic opportunities to cooperative agents. Can we design cash transfers to neutralize su...

We consider a family of jobs that are organized as a task-tree which, in particular, captures the behavior of divide-and-conquer algorithms in many typical cases (examples are QuickSort and Brute-Force Search jobs). These jobs can be described as a rooted task tree, where the cost of work at a node v in the tree is additive in the cost of v’s children. We give a lower bound on the time to perfo...

A natural and basic problem in scheduling theory is to provide good average quality of service to a stream of jobs that arrive over time. In this paper we consider the problem of scheduling n jobs that are released over time in order to minimize the average completion time of the set of jobs. In contrast to the problem of minimizing average completion time when all jobs are available at time 0,...

| The workload of many real-time systems can be characterized as a set of preemptable jobs with linear precedence constraints. Typically their execution times are only known to lie within a range of values. In addition jobs share resources and access to the resources must be synchronized to ensure the integrity of the system. This paper is concerned with the schedulability of such jobs when sch...